Migrate to GitHub Actions and update installation instructions.

Author: thomashoneyman

.github/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: CI
+
+on: push
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: purescript-contrib/setup-purescript@main
+        with:
+          purescript: "0.14.0-rc3"
+
+      - uses: actions/setup-node@v1
+        with:
+          node-version: "12"
+
+      - name: Install dependencies
+        run: |
+          npm install -g bower
+          npm install
+          bower install --production
+
+      - name: Build source
+        run: npm run-script build
+
+      - name: Run tests
+        run: |
+          bower install
+          npm run-script test --if-present

.gitignore

@@ -1,7 +1,7 @@
 /.*
 !/.gitignore
 !/.eslintrc.json
-!/.travis.yml
+!/.github/
 /bower_components/
 /node_modules/
 /output/

.travis.yml

@@ -1,7 +1,7 @@
 # purescript-refs
 
 [![Latest release](http://img.shields.io/github/release/purescript/purescript-refs.svg)](https://github.com/purescript/purescript-refs/releases)
-[![Build status](https://travis-ci.org/purescript/purescript-refs.svg?branch=master)](https://travis-ci.org/purescript/purescript-refs)
+[![Build status](https://github.com/purescript/purescript-refs/workflows/CI/badge.svg?branch=master)](https://github.com/purescript/purescript-refs/actions?query=workflow%3ACI+branch%3Amaster)
 
 This module defines functions for working with mutable value references.
 
@@ -10,7 +10,7 @@ _Note_: [`Control.Monad.ST`](https://pursuit.purescript.org/packages/purescript-
 ## Installation
 
 ```
-bower install purescript-refs
+spago install refs
 ```
 
 ## Example